By Jorn Madslien
BBC News Online business reporter at the Birmingham Motorshow

There is method to the apparent madness that has driven Porsche to chose Birmingham for the unveiling of the latest version of its flagship, the 911 Turbo S sportscar.

World premieres are few and far between in the UK

Serious sportscars have a particularly loyal following among British drivers, so in many ways a UK launch makes sense.

Porsche sells 8,000 cars a year in the UK, and this makes Britain the second largest market for its cars after the US, explains Andy Goss, managing director of Porsche Cars Great Britain.

"The UK customer is incredibly discerning," Mr Goss tells BBC News Online, insisting the 911 Turbo S is "the only world premiere" at this motorshow.

Now, that is not strictly the case, but it is correct that true world premieres are few and far between in the UK.

New versions

New, headline grabbing car models tend to be launched at more prestigious shows abroad, while Birmingham premieres are often new versions of existing models.

Porsche GB boss Andy Goss: "This business year will be the best ever"

And this year is no different - the new Porsche being a case in point. After all, this is not the first time we've seen a 911 with a turbo.

"Like it or not, it's the hierarchy of world motor shows," the UK general manager of Mini, Trevor Houghton-Berry - who chose to launch its latest convertible in Geneva in March - tells BBC News Online.

Other car makers perform similar stunts to Porsche's in Birmingham.

Land Rover's Discovery 3 TDV6 is hailed as a world first, yet it is virtually indistinguishable from previous models, while neither Volvo's jazzed-up V70 nor Nissan's new Primera will surprise visitors when the show opens for the public on Thursday.

Waiting list

But Porsche's 911 Turbo S is different, essentially because the German car maker's image relies heavily on its success.

Mr Goss sees no danger and is eager to recite statistics that paint a bright picture of his operation's future.

Falling 911 sales cause analysts to worry about Porsche's future

There is an eight month waiting list for 911 sportscars, he points out, then goes on to stress that the car maker's other models, the two-seater Boxster and the Cayenne sports utility vehicle, are doing very well too.

"Boxster will have its second-best year ever," he says, while Cayenne sales are "up 37% in the UK so far this year" when compared with the same period last year.

But while sales of the relatively ordinary Porsche models are roaring ahead, 911 sales are actually slipping back.

Mr Goss is keen to downplay the importance of this, insisting current sales are in line with Porsche's "budgeting" and that the fall in sales has come "as expected".

But nevertheless, analysts warn that if the four decades old 911 falls out of favour with serious sportscar buyers it could prove disastrous for Porsche.

Created buyers

One danger Porsche faces is that massive sales of its "not quite as upmarket" models might make the company's logo a common sight on the road, and this could make it less attractive to own the 911 flagship.

Is the Cayenne taking the Porsche brand downmarket?

This would be bad news for all three models: Boxster and Cayenne both compete with relatively ordinary luxury cars, and they both ride high on the image created by the 911 supercars.

Mr Goss is keen to dismiss any assertion that the Porsche brand has been diluted and points out that even the cheapest Cayenne, which is kitted out with a V6 Volkswagen engine, cost about £40,000.

The Cayenne has not caused drivers to desert Porsche, it has "created Porsche buyers", and that has helped to ensure that "this business year will be the best ever".

As such, there are good reasons to celebrate now, but concerns remain about Porsche's long-term health.